Pratik Mishra, Balamurugan Ramadass, Prasant Nayak, Rajan Jha
Real-time monitoring of human pulse signals is crucial for assessing cardiovascular health and detecting early signs of heart disorders. In this context, wearable systems offer a promising platform for continuous cardiac monitoring; however, existing devices suffer from complex fabrication, low accuracy, and limited body placement flexibility apart from bio-compatibility issues. To address these challenges, a wearable pulse monitoring system based on a flexible optical cavity has been developed and validated. The design employs a flexible polymer for both the cavity and the encapsulating material, enhancing mechanical strength and sensitivity compared to fiber cavity-based systems. The proposed device features a user-friendly and simple fabrication process and exhibits a high sensitivity of 610 pm/V under forced vibration, with a detection capability down to 0.1 Hz, enabling precise capture of subtle pulse wave impulses. Furthermore, it successfully monitors pulse signals from multiple body sites such as the wrist, elbow, and fingertip while distinguishing main, dicrowave, and tidal peaks. Its temperature stability and reliable performance under mild human motion, including arm movement, slow walking, and fast walking, even after physical activity, highlight its strong potential for continuous and practical cardiac health monitoring.